EntityFramework用法探索（四）Repository和UnitOfWork

以上一篇CodeFirst生成代码为基础，继续探索使用方式。

引入Repository模式，定义最简单的IRepository接口，仅包含增删改查接口，

public interface IRepository<T>
where T : class
{
IQueryable<T> Query();
void Insert(T entity);
void Update(T entity);
void Delete(T entity);
}

引入UnitOfWork模式，因为EntityFramework会负责失败回滚，所以此处只定义提交方法。

public interface IUnitOfWork
{
void Commit();
}

实现IRepository接口，

public class Repository<T> : IRepository<T> where T : class
{
private readonly IObjectSetFactory _objectSetFactory;
private readonly IObjectSet<T> _objectSet;

public Repository(IObjectSetFactory objectSetFactory)
{
_objectSetFactory = objectSetFactory;
_objectSet = objectSetFactory.CreateObjectSet<T>();
}

#region IRepository<T> Members

public IQueryable<T> Query()
{
return _objectSet;
}

public void Insert(T entity)
{
_objectSet.AddObject(entity);
}

public void Update(T entity)
{
_objectSet.Attach(entity);
_objectSetFactory.ChangeObjectState(entity, EntityState.Modified);
}

public void Delete(T entity)
{
_objectSet.DeleteObject(entity);
}

#endregion
}

实现IUnitOfWork接口，

public class UnitOfWork : IUnitOfWork, IDisposable
{
private readonly IObjectContext _objectContext;

public UnitOfWork(IObjectContext objectContext)
{
_objectContext = objectContext;
}

#region IUnitOfWork Members

public void Commit()
{
_objectContext.SaveChanges();
}

#endregion

#region IDisposable Members

public void Dispose()
{
if (_objectContext != null)
{
_objectContext.Dispose();
}

GC.SuppressFinalize(this);
}

#endregion
}

CustomerRepository类的实现需要做一些配置，

public CustomerRepository()
{
Mapper.CreateMap<DomainModels.Customer, Customer>();
Mapper.CreateMap<Customer, DomainModels.Customer>();

DbContext context = new RETAILContext();
DbContextAdapter contextAdaptor = new DbContextAdapter(context);

IObjectSetFactory objectSetFactory = contextAdaptor;
_repository = new Repository<Customer>(objectSetFactory);

IObjectContext objectContext = contextAdaptor;
_uow = new UnitOfWork(objectContext);
}

则具体增删改查的逻辑实现，

public void InsertCustomer(DomainModels.Customer customer)
{
Customer entity = Mapper.Map<DomainModels.Customer, Customer>(customer);

_repository.Insert(entity);
_uow.Commit();

customer.Id = entity.Id;
}

public void UpdateCustomer(DomainModels.Customer customer)
{
Customer entity = _repository.Query().Single(c => c.Id == customer.Id);

entity.Name = customer.Name;
entity.Address = customer.Address;
entity.Phone = customer.Phone;

_repository.Update(entity);

_uow.Commit();
}

在同样的示例下仍然可以工作，

ICustomerRepository customerRepository = new CustomerRepository();

// =============== 增 ===============
Console.ForegroundColor = ConsoleColor.DarkRed;

DomainModels.Customer customer1 = new DomainModels.Customer()
{
Name = "Dennis Gao",
Address = "Beijing",
Phone = "18888888888",
};
customerRepository.InsertCustomer(customer1);
Console.WriteLine(customer1);

同时，UnitOfWork可以保证相关的业务操作在同一个Transaction中，

完整代码和索引

EntityFramework用法探索系列

（一）DatabaseFirst

（二）CodeFirst

（三）CodeFirst流畅API

（四）Repository和UnitOfWork

（五）引入Unity

（六）静态Repository

（七）线程安全实践

（八）事务处理

完整代码下载